1. Photomineralization of aqueous salicylic acids. Photoproducts characterization and formation of light induced secondary OH precursors (LIS-OH)
- Author
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Abdelaziz Boulkamh, Claire Richard, Mohamad Sleiman, R. Tafer, Institut de Chimie de Clermont-Ferrand (ICCF), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-SIGMA Clermont (SIGMA Clermont)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Université frères Mentouri Constantine I (UMC), and Université des Frères Mentouri, Laboratoire des Techniques Innovantes de Préservation de l’Environnement
- Subjects
BSTFA ,Environmental Engineering ,Light ,Radical ,Carboxylic acid ,02 engineering and technology ,010501 environmental sciences ,Photochemistry ,01 natural sciences ,Absorbance ,Derivatization agents T-Box ,chemistry.chemical_compound ,OH radical ,[CHIM]Chemical Sciences ,Phenols ,Photodegradation ,Waste Management and Disposal ,0105 earth and related environmental sciences ,Water Science and Technology ,Civil and Structural Engineering ,chemistry.chemical_classification ,Aqueous solution ,Photolysis ,Hydroxyl Radical ,Ecological Modeling ,Photodissociation ,Water ,021001 nanoscience & nanotechnology ,Substituted phenols ,Pollution ,Photobleaching ,Salicylates ,Hydroperoxides ,chemistry ,DNPH ,0210 nano-technology - Abstract
International audience; The photolysis of aqueous 5-chlorosalicylic acid (ClSA) and dihydroxybenzoic acid (DHBA), its main photoproduct, was studied to determine the extent of degradation caused by simulated solar light. Photoproducts identification was achieved using high resolution LC-MS and GC-MS. About 40 photoproducts from C19 to C1 were characterized, including a dihydroxycyclopentadienic acid, a ring contraction photoproduct, and numerous carbonyls and carboxylic acid derivatives that were detected thanks to derivatization. UV–visible spectral monitoring of the reactions revealed that ClSA and DHBA underwent photobleaching after developing a temporarily featureless absorbance between 300 and 500 nm. Measurement of OH radicals using terephtalic acid as a probe showed that OH radicals were generated with an average rate of 7 × 10−9 M s−1 and a total cumulated concentration of 10−3 M, corresponding to ∼ 5-fold the initial concentration of DHBA. Furthermore, TOC analysis indicated that significant mineralization (51–90%) occurred. These findings are consistent with the formation of light induced secondary OH (LIS-OH) precursors such as featureless long wavelength absorbing compounds as well as non-absorbing hydroperoxides. The formation of LIS-OH illustrated here may also take place in the aqueous photodegradation of other substituted phenols likely present in dissolved organic matter and humic substructures, it deserves to be studied in more details.
- Published
- 2016